Radiofrequency amplifying system



y 3 R. B. BENJAMIN 1,807,300

RADIOFREQUENCY AMPLIFYI NG SYSTEM Filed Oct. 6, 1927 lime/2hr:

Patented May 26, 1931 UNITED STATES PATENT OFFICE REUBEN B. BENJAMIN, OF CHICAGO, ILLINOIS, ASSIGNOR TO BENJAMIN ELECTRIC MFG. COMPANY, OF CHICAGO, ILLINOIS, A. CORPORATION OF ILLINOIS RADIOFREQUENCY AMPLIFYING SYSTEM Application filed October 6, 1927. Serial No. 224,323.

My invention relates to tuning and couling means such as might be used in a radio requency amplifying system.

One of the objects of my invention is to provide in a radio frequency amplifying system, means for coupling the output of one audion tube to the input of another tube, tuning the input circuit of the second tube and equalizing the transfer of energy from tube to tube at all positions of the tuning means, which construction can be made up in compact unitary form.

A further object of my invention is to provide such a construction which-can be readily shielded. Y

A further object of my invention is to provide a device of the character indicated above which will be rugged in construction, easy to assemble, cheap to manufacture, and durable in use.

A further object of my invention is to provide a device of the character indicated above for use with a tuning condenser of the concentric plate type:

A further object of my invention is to provide a device of the character indicated above, which lends itself readily to gang construction.

Further objects will appear scription and claims.

In the drawings in which an embodiment of my invention is shown,

Figure 1 is an axial sectional view of a tuning and coupling device embodying my invention;

Fig. 2 is a section on the line 22 of Fig. 1;

Fig. 3 is a section on the line 3-3 of Fig. 1

Fig. 4 is a side elevation of the device;

Fig. 5 is a bottom section thereof; and

Fig. 6 is a diagrammatic view showing the wiring.

Referring to the drawings in detail, the construction shown comprises means for coupling the output of one audion tube 1 to the input of another tube 2, tuning the input circuit of one of the tubes and equahzing the transfer of energy from tube to tube atall positions of the tuning means, comprising a stationary condenser element 3 of circular outline having cylindrical plate members 4,

from the dea movable condenser element 5 of circular outline having cylindrical plate members 6 intermeshable with the stationary plate members, a fixed coil member 7 of circular outline in the primary circuit of the transformer, a second fixed coil 8 of circular outline also in the primary circuit of the transformer, a movable coil member 9 of circular outline comprising a coil 10 connected between the two fixed coils 7 and 8 in the primary circuit, and a coil 11 in the secondary circuit, a shaft 12 for effecting movement of the movable condenser element 5 and movable coil element 9, a cylindrical housing member 13 surrounding the coils and movable condenser element, and a circular head 14 which cooperates with the stationary condenser element 3 and cylindrical housing 13 to enclose the movable condenser member 5 and the coils to shield them electrically and prevent foreign material from coming into contact with the condenser plates and coils. The movable condenser element and movable coil are both mounted on a sleeve 15 which sleeve has a threaded engagement with a helical groove 16 in the rotatable actuating shaft 12. The movable condenser element is held from rotating with the rotatable shaft by means of a lug 17 secured thereto which slides between a pair of guides 18 formed as integral parts of a curved sheet metal member 19 which fits just inside the cylindrical casing member 13 and is adjustably secured thereto so as to be capable of a limited angular adjustment about the axis of the actuating shaft. This curved plate may be held in any position to which it may be adjusted by means of a pair of screws 20 which extend through helically extending slots 21 in the cylindrical casing member 13 and are threaded into the curved plate 19. The purpose of this an nlar adjustment of the guide plate is to ena 1e the minimum capacity of the condenser to have a limited adjustment. It will be seen that the minimum capacity of the condenser will be varied by shifting the guide plate angularl as this will move the movable condenser e ement in or out with respect to the stationary condenser element. No claims are made to this feature broadly in this applicaconcerned,)

tion, as it is claimed in my co-pending application, Serial No. 154,334.

The slots 21 are helically arranged in the casing 13 in order notto interfere with an adjustment of the stationary adjustable coils 7 and 8 hereinafter described. As the movable coilmember 9 is mounted on the sleeve 15 on which the'non-rotatable movable condenser element 5 is mounted, it follows that this coil will move back and forth with the movable condenser element traveling between the two fixed adjusted coils 7 and 8, approaching the right hand coil 8 as seen in Fig. lwhen the condenser is adjusted to lessen the capacity, and approaching the left hand adjusted stationary coil 7 when the condenser is adjusted to increase the capacity.

As shown in Fig. 6 the primary winding of the transformer construction comprises the adjusted coil 7, the coil 10 in the movable coil member, (which coil 10 is the principal member'of the primary part of the transformer so far as the transfer of energy is and the second adjusted coil 8, the fixed adjusted coil 7 being connected to the plate of the preceding tube 1, and the second adjusted coil being connected to the positive side of the B battery. The first adjusted coil 7 is so designed that it acts in the same direction as. the intermediate movable primary coil 10 on the secondary coil 11 of the transformer while the second adjusted primary coil 8 is so designed as to 0ppose the energy transferring effect of the intermediate coil 10 of the primary transformer on the secondary transformer coil 11. With this construction it will be seen that the ener y transferring effect of the transformer will be increased as the movable coil carrying member 9 is shifted toward the first adjusted primary member 7, and will be decreased as the movable coil carrying member 9 is shifted toward the second adjusted primary coil 8. This first movement referred to, which increases theenergy transferring effect, also brings the movable-member 5 of the condenser closer to the stationarymember 3 of the condenser to increase the capacity effect in tuning for lower frequencies. Similarly, in tuning for higher frequencies, the energy transferring efficiency of the transformer construction is decreased. This result is desirable in tuned radio frequency amplifiers these parts used in radio frequency amplifiers, the movable condenser element 5 and one side of the coil 11 of the secondary being connected with the grid of the following tube 2 and the stationary element 3 of the condenser, and the other end of the secondary 11 of the transformer being connected with the negative side of the A battery.

In order to provide.for an adjustment of the assisting and opposing effects of the two adjusted coils, these are so mounted that they can be adjusted to be brought closer to or farther from the movable coil carrying mem ber 9; for this purpose each of these coils is mounted 011 a framework having a plurality of arms 22 provided with outwardly extending lugs 23 which work in helical slots 24 in the cylindrical housing 13 so that as this framework is angularly adjusted with respect to the cylindrical casing the coil will be caused to approach or recede with respect to the movable coil carrying member. For holding these adjusted coils 7 and 8 in adjusted position a screw 25 is provided which works in a helical slot 26 in the adjustable plate 19 previously referred to, this screw being threaded into a curved plate 27 which is engaged by three of the laterally extending arms 28 of the insulating frame 29 on which the coil is wound. Two of these arms 28 straddle this curved plate 27, being recessed as indicated at 30 to accommodate the ends respectively of this curved plate with which the setting screw 25 has threaded engagement. The cylindrical casing 13 is provided with helical slots 31 in which the heads of the setting screws 25 may move and which slots provide for access to the heads of these screws. As the pitch of the helical slots 31 and 26 is the same as the pitch of the helical slots 21, it follows that the curved plate 27 may be adjusted as a whole without any interference in this movement from the heads of the screws engaging the sides of the slots.

In order to hold the actuating shaft 12 against endwise movement a split washer 32 is provided on the inside of the head which springs over a reduced portion of this shaft and is thus held in place against endwise movement thereon, and a spring spider 33 is slipped on over the shaft on the outside of the head and is held against endwise movement on the shaft by means of a set collar 34 secured to the shaft by means of a set screw 35. Any suitable actuating device, such as an insulating knob may be secured on the reduced portion 36 of theactuating shaft. The cylindrical casing member 13, the fixed condenser element-3, and the circular head 14, may be held in place with respect to each other to form a housing by means of screws 37 extending through the flange on the condenser element 3 and threaded into the circular head 14. The circular head 14 and fixed condenser elements may be provided with circular grooves to receive the edges of the cylindrical housing member. The circular head may be provided with interiorly threaded bosses 38 to facilitate its'attachment to a supporting panel.

It will be seen that the construction described provides a device for coupling the output of one audion tube to the input of another tube, tuning the input of the second tube and equalizing the transfer of energy from stage to stage which can be made up in a compact unitary form in which the parts may be readily shielded and in which the construction will be rugged, easy to assemble, cheap to manufacture, and durable in use. It will also be seen that this construction is suitable for use with a condenser of the concentric plate type and that it lends itself readily to gang construction as a gang construction would involve simply the stringing of several of these units on a common actuating shaft as disclosed in my prior application, Serial No. 154,334.

While I have disclosed but one embodiment of my invention, modifications thereof may occur to those skilled in the art, and I desire, therefore, that my invention be limited only by the scope of the appended claims and by the prior art.

1. In a radio frequency amplifying system, means for coupling the output of one audion tube to the input of another tube, tuning the input circuit of one of the tubes, and equalizing the transfer of energy from tube to tube at all frequencies of the tuning means, said means comprising a movable tuning condenser element, a shaft for actuating said element, and a coil actuated by said shaft and shiftable thereby longitudinally of the axis of the shaft, said coil lying substantially within the confines of a surface defined by a line moved so as to remain parallel to the axis of said shaft and so as to follow the periphery of said movable tuning element.

2. In a radio frequency amplifying system, means for coupling the output of one audion tube to the input of another tube, tuning the input circuit of one of the tubes, and equalizing the transfer of energy from tube to tube at all frequencies of t e tuning means, said means comprising a movable tuning condenser element a shaft for actuating said element, and a coupling varying device actuated by said shaft and shiftablethereby lon' gitudinally of the axis of the shaft, said coupling varying device lying substantially within the confines of a surface defined by a line moved so as to remain parallel to the axis of said shaft and so as to follow the periphery of said movable tuning element.

3. In a radio frequency amplifying system, means for coupling the output of one audion tube to the input of another tube, tuning the input circuit of one of the tubes, 65 and equalizing the transfer of energy from tube to tube at all frequencies of the tuning means, said means comprising a movable tuning condenser element, a rotatable shaft for actuating said element, and a coil actuated by said shaft and shiftable thereby longitudinally of the axis of the shaft, said coil lying substantially within the confines of a surface. defined by a line moved so as to remain parallel to the axis of said shaft and so as to follow the periphery of said movable tuning element.

4. In a radio frequency amplifying system, means for coupling the output of one audion tube to the input of another tube, tuning the input circuit of one of the tubes, and equalizing the transfer of energy from tube to tube at all frequencies of the tuning'means, said means comprising a movable tuning condenser element, a shaft for actuating said element to shift it lon itudinally of the axis of the shaft, and a COll actuated by said shaft and shiftable thereby longitudinally of the axis of the shaft, said coil lying substantially within the confines of a suface defined by a line moved so as to remain parallel to the axis of said shaft and so as to follow the periphery of said movable tuning element.

5. In a radio frequency amplifying system, means for. coupling the output of one audion tube to the input of another tube, tuning the input circuit of one of the tubes, and equalizing the transfer of energy from tube to tube at all frequencies of the tuning means, said means comprising a movable tuning condenser element, a shaft for actuating said element, and a. coil actuated by said shaft and shiftable thereby longitudinally of the axis of the shaft, said movable tuning element and coil being circular in form and having substantially the same diameter and axis. 1

6. In a radio frequency amplifying system, means for coupling the output of one audion tube to the input of another tube, tuning the input circuit of one of the tubes, and equalizing the transfer of energy from tube to tube at all frequencies of the tuning means, said means comprising a movable tuning condenser element, a shaft for actuating said element, and a coil actuated by said shaft and shiftable thereby longitudinally of the axis of the shaft, said movable tuning element and coil being circular in form and having substantially the same diameter and axis, and a cylindrical housing enclosing said tuning element and coil. I

7. In a radio frequency amplifying system, means for couplingthe output of one audion tube to the input of another tube, tuning the input circuit of one of the tubes, and equalizing the transfer of ener y from tube to tube at all frequencies 0 the tuning means, said means comprising'a movable tuning condenser element, a shaft for actuating said element, and a coil actuated by said shaft and shiftable thereby longitudinally of the axis of the shaft, said shaft extending through said coil.

8. In a radio frequency amplifying system, V 5 means for coupling the output 0 one audion tube to the input of another tube, tuning the input circuit of one of the tubes, and equalizing the transfer of energy from tube to tube at all frequencies of the tuning means, 10 said means comprising a movable tuningcondenser element, a shaft for actuating said elementto shift it longitudinally of the axis of the shaft, and a coil actuated by said shaft and shiftable thereby longitudinally of the 15 axis of the shaft, said shaft extending through said tuning element and coil.

9. In a radio frequency amplifying system, means for coupling the output of one audion tube to the input of another tube, go tuning the input circuit of one of the tubes, and equalizing the transfer of energy from tube to tube at all frequencies of the tuning means, said means comprising a stationary condenser element of circular outline having a cylindrical plate members, a movable condenser element of circular outline having cylindrical plate members intermeshable with said first plate members, a fixed coil member of circular outline, a movable coil member of so circular outline, said circular outlines having substantially the same diameter and axis, a shaft for actuating the movable condenser element and the movable coil extending through said coils and movable condenser ele- 8! ment, and the cylindrical housing member surrounding said coils and movable condenser element, the stationary condenser element closing the end of said cylindrical housing member and cooperating therewith to form a Q housing for the coils and movable condenser element.

In witness whereof, I have hereunto subscribed my name.

REUBEN B. BENJAMIN. 

